(1) Field of the Invention
The present invention relates to a clutch target position control system wherein the clutch position is determined on the basis of the throttle opening, the engine revolutional speed, and the input shaft revolutional speed.
The present invention also relates to an automatic clutch system, in particular, to a clutch control system wherein the clutch target position and the clutch speed are automatically controlled.
(2) Description of the Related Art
Conventionally, the target engagement position of an automatic clutch is determined in relation only to the accelerator pedal depression movement, as disclosed in Japanese Unexamined Patent Publication (Kokai) No. 60-11756. However, the engine revolutional speed is high before the clutch is engaged and drops after the clutch is engaged, and thus it is very difficult to control the clutch, in such a manner that a smooth driving of the car is realized, with the prior art control system when the engine speed is slow and in response to the above-mentioned engine revolutional speed change.
In a prior art automatic clutch system, the clutch speed is controlled in accordance with the driving condition of the car, which condition is classified into three driving modes as described below.
(1) Slow Speed Mode: The clutch target position is determined on the basis of the accelerator pedal depression movement. The clutch speed, i.e., the speed of the clutch plate, is compensated in response to the clutch position.
(2) Start Mode: A basic clutch speed is determined on the basis of the accelerator pedal depression movement. The clutch is controlled by compensating the basic clutch speed in response to the clutch stroke and the engine revolutional speed change.
(3) Shift Mode: A basic clutch speed is determined on the basis of the accelerator pedal depression movement. The clutch is controlled by compensating the speed in response to the difference between the engine revolutional speed and the input shaft revolutional speed.
In the above-mentioned prior art clutch control system, the clutch target position and the clutch speed are determined on the basis of different parameters, respectively. The operation is divided into three modes, and thus a complicated algorithm must be prepared. Further, another independent algorithm for disengagement of the clutch at the time of releasing the accelerator pedal must be prepared.
The afore-mentioned three modes are used to control the engagement of the clutch. To control the disengagement of the clutch, in the slow speed mode, a minimum engine revolutional speed in relation to engine stall is predetermined, and when the actual engine revolutional speed reaches the predetermined value, the clutch is disengaged. In the start mode, a minimum engine revolutional speed in relation to the clutch position is predetermined, and when the actual engine revolutional speed reaches the predetermined value, the clutch engagement movement is stopped. When the engine revolutional speed is further lowered, the clutch is controlled in the same manner as in the slow speed mode. With such a control system in the slow speed mode and start mode, when a sudden torque change is applied to the engine due to a steep slope or a sidewalk curb, the clutch disengagement movement due to the engine speed reduction and clutch engagement movement due to the engine speed restoration are repeated, which causes the engine to stall and makes the driver feel unconfortable. Also, the algorithm is complicated due to the many control modes and control parameter data, which results in time wastage when selecting the data.